1. A branch of mathematics in which symbols, usually letters of the alphabet, represent numbers or members of a specified set and are used to represent quantities and to express general relationships for all members of the set to solve problems involving finite numbers.
2. Etymology: from Medieval Latin which came from Arabic al jebr or al-jabr, "reunion of broken parts", as in computation, used in the 9th century by Baghdad mathematician Abu Ja'far Muhammad ibn Musa al-Khwarizmi as the title of his famous treatise on equation, Kitab al-Jabr w'al-Muqabala, "Rules of Reintegration and Reduction"; which also introduced Arabic numerals to the West.

The accent in pronunciation moved in the 17th century from the second syllable to first syllable. The word was used in English in the 15th century to the 16th century to mean al-, "the" + jabr, "bone-setting, restoration" (from jabara, "to set (bones), to force, to restore"; perhaps from the Arabs in Spain.